Converting hydrocarbon oils



Oct. 18, 1932. o. BEHIMER CONVERTING HYDROCARBON OILS 4 Sheet-Sheet 1 Original Filed Aug. 6, 1920 Illlll'lllllllllll flH llll ll! I l l ll avwentoz 0. BEHIMER 4 Sheets-Sheet 2 CONVERTING HYDROCARBON OILS Original Filed Aug. 6. 19 20 HHI I I IHH I IH I Oct. 18, 1932.

vwan oi Oct. 18, 1932. o. BEHIMER 1,883,491

CONVERTING HYDROCARBON OILS Original Filed Aug. 6. 1920 4 Sheets-Sheet 4 INVENTOR ATTORNEY Patented Oct. 18, 1932 UNITED STATES PATENT OFFICE OTTO BEHIMER, 01' OAK- PABK, ILLINOIS, ASSIGNOIR TO THE TEXAS COMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE CONVERTING HYDROCARBON' OILS this application filed November 26, 1927.

This invention relates to methods and apparatus for making condensable light oils, such as gasoline and naphtha, and is closely related to and constitutes a modification of that set forth in my pcndin application, Serial Number 263,562, filed ovember 21, 1918.

This application is a division of my copending application, Serial Number 401,623, filed August 6, 1920.

In this earlier application, Ser. No. 263,-

" 562,1 have described a process in which the oil is first heated to a cracking temperature or to a temperature exceeding that necessary for decomposition while it flows through a coil at such a high velocity that little or no decomposition actually takes place in the coil, but is effected in a drum or still into which the coildischarges. The drum or still is either insulated or heated sufliciently to prevent loss of heat due to radiation, and the heat contained in the oil is utilized to effect the desired decomposition, the oil being heldat a cracking temperature for a time sufficient to convert higher boiling hydrocarbons into the desired lower boiling hydrocarbons. By such a method of operation I have been able to avoid what has hitherto been a serious objection to all cracking operations employing heat and pressure, viz, the short life of the converters due to the deposition of carbon upon the highly heated surfaces of the stills and tubes with the consequent overheating and deterioration of the metal.

In accordance with my present invention the oil to be converted, which is first preheated, preferably by means of waste heat, is passed through a highly heated coil so that the oil will absorb a large quantity of heat and attain a suflieiently high temperature for cracking. However, the rate of flow of oil through the coil is very rapid, and is so regulated that the oil is not in the coil for a time suflicient to permit any material decomposition, consequently there is no appreciable deposition of carbon in the tubes. The oil in a state of incipient conversion is then passed into a plurality of converters or cracking stills in which it is held at a crack- No. 401,623, and in Canada December 3, 1921. Divided and Serial No. 235,804.

ing temperature for the time necessary for decomposition, the necessary heat for maintaining a conversion temperature being supplied by moderate heating of the stills, although loss of heat may be prevented by thorou lily insulating the stills.

The l iighly heated oil is charged from the heating coil directly into one or more of the stills or converters and flows to the others in series. One or more of the cracking stills serve the purpose of carbon and residue collectors as well as converters and enable the removal of the residue including carbon and heavy polymerized products from the system in an effective manner. The operation is carried on with a positive flow of cracking oil through the successive converters thus preventing the apparatus from being clogged with carbon and insuring the withdrawal of the residual products. The vapors and gases generated are passed to suitable separators whereby those of less volatility than desired are condensed and after being mixed with the oil charge are returned to the heating coil,

the vapors of desired volatility being withdrawn and condensed as a desired final product.

By using two or more converters the large scale production of gasoline is facilitated with a high degree of economy and safety because the oil may be charged into one converter and the carbon may be effectively separated by drawing ofl the residrie from another converter, where the bottom liquid is not dis- 'turbed by the admission of either the oil charge or the backtrap. The intermediate or heavy distillates formed, that is, those of higher boiling point than desired for the final product, such as for example the kerosene fractions, are separated out from the vapors generated and are thus returned continuously as formed to the heating coil so that the ratio of charge to backtrap or returned condensate is substantially eonstant for a given mode of operation.

In order to more fully disclose my invention I have illustrated in the drawings a preferred form of apparatus adapted for carrying out the invention and constituting an embodiment thereof.

In the drawings Figure l is a general diagram of a conversion apparatus arranged and constructed in accordance with my invention and adapted for practicing the same.

Figure 2 is a partially diagrammatic elevation of the same apparatus including the converters, the separators, the condenser, the receiver, and their connections.

Figure 3 is a partially sectional elevation of the heating coil on the line 3-3 of Figure 4. v

Figure 4 is a sectional elevation of the heating coil and its furnace, taken at right angles to Figure 3.

Figure 5 is a detail view of the separator drum drawn to a larger scale.

Figure 6 is a transverse sectional view of a modified form of separator drum which may be substituted for the Figure 5 construction.

Figure 7 is an elevation of another form of separator which also performs the functions of a preheater.

Figure 8 is a partial diagram of a conversion apparatus embodying a battery of four cracking stills.

Referring to the drawings The several component elements of the apparatus'may be generally characterized as a heat exchanger A, an economizer B, a heating coil C, a cracking zone D, a separating device E, a condenser F and a collector G.

A pump 1 is connected to a suitable source of oil supply (not shown) and is adapted to force the oil to be converted to the heating coil C. Preferably, however, the oil is not supplied directly to the heating coil C and, as illustrated, the exchanger A and theeconomizer B are interposed between the pump and the coil C. The connection is established by a pipe 2, a coil 3 in the exchanger drum 4, a pipe 5, a preheating coil 6 of the economizer B, and a pipe 7 which discharges into the heating coil 8 of heater C. The coils 3 and 6 are preferably heated by means of waste heat in a manner hereinafter set forth.

The coil 8 is arranged to be subjected to a high degree of heat and the construction may conveniently take the form of that shown in Figures 3 and 4, in which 9 designates the furnace in which the coil 8 is supported. The furnace has a perforated baflie 8a to insure complete combustion and uniform distribution of the gases before they reach the tubes. Thegases after giving up heat to the rapidly flowing oil in the tubes pass out through the flue 10.

The outlet 11 of the heating coil 8 extends l coil C at suflicient rate to keep its contents agitated and prevent much carbon deposit, and another may constitute a residue collecting still from which the undisturbed bottom can be drawn off effectively. Any suitable number of stills may be used such as, for example, a battery of six, the number of re ceiver and residue collecting stills being proportioned as desired. For instance, the oil may be charged into three stills and-withdrawn from the other three or the charge may be run into four and the residue collected in and drawn off from the other two. Ordinarily I prefer to draw off from as few stills as possible in order to increase the flow of oil through the draw-oil still or stills.

In the embodiment of the invention shown in the drawing the cracking zone D, for simplicity and convenience, consists of the two stills 12 and 13 which are intended to be illustrative of any suitable number.

The pipe 11 from the heating coil 8 has a valve l t, and is connected to still 12 near the bottom, while a connection is established from the still 12 to the still 13 by 'a liquid flow line 15 and a vapor equalizing line 16.

The conversion of the oil takes place in the stills of the cracking zone D, although the heat necessary for decomposition is supplied to the oil largely while it flows through the highly heated coil 8. Therefore it is not necessaryito apply such high furnace temperatures to the stills as have been considered essential in the past to the operation of cracking stills. In fact, the process may be conducted without supplying external heat to the stills (except at the start of a run until decomposition sets in) provided the stills are insulated against loss of heat. However, I prefer to install the converters in a furnace and to supply only suflicient heat to compensate for losses and to maintain the converters at a proper cracking temperature. If desired, the stills may be internally heated by electricity.

The stills 12 and 13 are disposed in a furnace 17, as shown in dotted lines in Figure 2, with their lower ends extending below the heating zone and thusshielded from the direct furnace heat, and their upper ends extending into a cool space above the brickwork. Each still is thus provided with a relatively cool bottom where the carbon may collect without danger of burning out the walls of the still and a vapor space free from the direct furnace heat which would'tend to produce large volumes of fixed gases and burn the still at the liquid level.

At even the comparatively low furnace temperatures applied to the stills in my process, there is a relatively slight tendency for carbon to deposit on the walls and, for, this reason, it is best'to provide each still with scraping mechanism to keep the interior metal surfaces free of carbon. As shown in Figure 2, each still is preferably equipped with a shaft 18 which carries suitable brushes or scrapers 19 and is rotated by a power driven shaft 21 through the action of gears 20. The scraper shafts may be journaled in any suitable manner, but it is preferable to avoid a hearing at the bottom of the still where carbon or residue collects. Each shaft extends above the still at the top through a stuffing box 22 mounted on a pipe 23 which is of suflicient length to prevent overheating 0 and disruption of the stuffing box. The carbon removed from the heated walls is allowed to gravitate out of the heating zone.

The converters are equipped with suitable means for withdrawing the residue and carbon from the system. Preferably a pair of draw-ofi lines are provided for each still so that in case one line should become choked up with carbon the remaining line will be available. Thus, the still 12 is equipped with the outlet pipes 24 and 25 having the valves 26 and 27 respectively, and the still 13 has the outlet pipes 28 and 29 controlled by the valves 30 and 31, respectively. The outlets terminate in the common residue line 32 which preferably extends to the exchangerdrum 4 and thus heats the oil flowing through the coil 3. The exchanger drum 4 is provided with the valve controlled draw-off 33 by which the carbon and residue may be removed as desired. In any case the residue is discharged entirely from the system and no part thereof is retreated in the heating or cracking zone. It is well to provide the con- 0 verters with additional valve controlled outlets 34 located at the extreme bottom of the stills; for instance, available for drawing off any water which may collect in the stills at the beginning of a run due to moisture contained in the oil operated on and also to expedite thedraining of the stills at the end of a run.

To correctly indicate the liquid level in each still, a piping 37 is provided, having a U bend 38 and an inverted U bend 39, and a gage 40 is attached to the vertical portion of the piping, asi'llustrated. \Vit-h this con struction the U bend 38 forms a liquid seal of relatively cool oil and the bend 39 forms a comparatively cool gas pocket, thereby protecting the gage from the heat of the still and making possible a correct reading on the gage.

The gage mounting shown and described is not claimed herein as it is set forth and claimed in my Patent No. 1,526,312, granted February 17, 1925 and assigned to-The Texas Company.

The vapor line 41 extends from the still 13 to a suitable separating device or reflux condenser E. The type of separating device shown comprises a primary separator 42 and a secondary separator 43. Additional sections may be employed, if desired. For example, I may provide a triplex arrangement in which the several sections may be referred to as the primary or heavy separator, the intermediate separator and the light separator. However, the principle involved is substantially the same regardless of the number of sections and will be clearly understood from the duplex form illustrated.

The heavy separator 42 consists of a lower drum or header 44, preferably of cylindrical form, and a similar upper drum 45, connected to each other by a series of vertically extending pipes or risers 46. The vapor line 41 may comprise one or more pipes extending from the vapor space of the still 13, the entrance of a pair of lines into the drum 44 being clearly shown in Figure 5.

A vapor line 47 extends from the to of the drum to the lower drum 48 o the light separator 43, which is similar in construction to the primary separator, having an upper drum 49 and the plpes 50 connecting the upper and lower drums. The condensate pipe 51, which may have a valve 52, extends from the lower part of the drum 48 to the upper plart of the drum 44 and thus serves to bring t e condensate from the light separator into contact with the vapors entering the drum 44 from the vapor line 41. In order to more efliciently utilize the heat of the vapors for redistilling the condensate the drum 44 is provided with a distilling pan 53 into which the reflux from the secondary condenser may be discharged. In the modified form of apparatus shown in Figure 6 a pair of baflle plates 54 are provided upon which the backtrap flows. The condensate dropping in the pan 53 or flowing over the distilling plates 54 is revaporized by the heat of the vapors entering the drum 44.

The primary function of the air condensers E, or any other type of separator which may be em loyed in connection with the herein descril jed process, is to separate out from the mixed vapors passing out of the vapor line 41 those hydrocarbons which are less volatile than desired for the final product and to trapthose constituents without substantial loss in heat and enable them to be returned in cyclic passage through the heating coil C and the converters D. To accomplish this I provide a backtrap return line 55 having a valve 73 which extends from the bottom of the primary separator to the heater C. A heat cycle is thus generated which assists in the maintenance of the required heat in the converters and the kerosene and like constituents are ultimately decomposed into the volatile products desired. The backtrap may be admitted to the heating coil 8 in any suitable manner. As shown in Figure 1 the condensate is pumped by means of an oil. pump 56 and positively forced into the rapidly flowing stream of charging oil and thence into the coil 8. As illustrated in Figure 4 the return condensate may be injected into the oil charge entering the heating coil by means is condensed out in the separators E and forthis reason it is well to provide facilities for draining oil the water. Thus the line 55 having a valve 73 is provided with a branch line 74 connecting with a branch pipe which extends downwardly from the condensate line 51. The pipe 74 has a valve 76 and the pipe 75 has a valve '77, the two pipes terminating in a draw-ofi' line 78. By closing the valve 73 and opening either or both of the valves 76 and 77 liquid maybe drawn off through either or both of the pipes 74 and 75.

The vapors uncondensed in the separating device E pass into the vapor line 58 which terminates in the coil 59 located in the condenser box 60 of the condenser F, the box being supplied with water or any suitable cooling medium. A control valve 61 may be placed in the line 58, as shown in Figure 1. However, it is generally more convenient to place the control valve in the condenser outlet 62 as shown in Figure 2 at 63. The line 62 terminates in suitable mechanism for collecting the distillate, as the receiver 64 which is equipped with a gas outlet 65, having the valve 66 and a condensate outlet 67 having a valve 68. The distillate line 62 may be provided with a valved branch line 69 as it is sometimes convenient to draw oil oil from the condenser without admitting it into'the receiver 64.

I prefer to install the heating coil C and converters d in separate furnaces located as close together as practicable in order to make the connecting pi e 11 as short as possible and avoid loss of eat during the transmission of the oil from the heating coil to the converters. The waste heat from these two furnaces may be advantageouslyutilized to heat the economizer coil In Figure 8 a battery of four cracking stills 12a, 12b, 13a and 13b is shown and the outlet of the heating coil C is branched to provide a line 11a extending to the still 12a and a line 11?) extending to the still 12b.

Itis understood that the apparatus described herein may be equipped with thermometers, or pyrometers, pressure gages and other well known accessorles which need no explanation to those skilled in the art to which my invention pertains. However, in order to use my invention to the best advantage certain parts of the apparatus should be equipped with temperature recording devices, as the thermometer 70, in the connecting line 11, and the thermometers 72 in the se arators.

y process is adapted for converting any higher boiling oil into lower boiling hydro-- carbons. For example, crude oil, or the residue thereof from which the lighter oils have been previously distilled, or distillate such as kerosene and gas oil may be treated by my process and converted into lower boiling hydrocarbons. I prefer, to use a distillate such as gas oil,' or possibly a mixture of a distillate with a residuum, on account of the smaller proportions of carbon formed in cracking distillates than are produced in cracking residual oils. However, as a result of my method of utilizing the heavier distillates such as the kerosenefractions formed in the cracking operation for diluting the charge entering the heating coil, it is possible by means of my invention to successfully manufacture gasoline and similar light products from heavy residual oils.

The oil to be converted is heated in the coil C to a cracking tem )erature or higher and is then held at a crac ring temperature in the stillsl) long enough to causemolecular decomposition and formation of light hydrocarbons, the oil being-under a superatmospheric pressure of the generated vapors and gases. Ordinarily I do not employ pressures IIllICh lower than 100 pounds, due to the fact that the rate of decomposition is too slow under the lower pressures for the most eificient method of operation. I prefer to use pressures around 200 pounds and while Imay at times employ higher pressures, such as 400 pounds, I have found that it is not generally necessary to use the higher pressures, as good results can ordinarily be obtained at pressures ranging from 150 to 250 pounds.

The oil to be converted is forced by'the pump 1 through the preheating coils 3 and 6 of the heat exchanger and the econom zer. Sometimes it is not necessary to use both preheating coils and the charge may be byassed around the one or the other. It is best, cwever, to preheat the oil before it enters the coil 8 so to reduce as far as possible the large quantity of heat which must be applied to this coil. As the oil circulates through the coil 8 it absorbs heat and is elevated to a cracking temperature or even higher so that the incipient stages of decomposition have set in before it leaves the coil to enter the stills. It is to be noted that I do not gasify or vaporize the whole body of the oil in the coil, as I desire to avoid the disadvantages of the vapor phase processes which are always accompanied with a large production of fixed gases and carbon. The oil leaving the coil 8 is substantially in liquid form and at a cracking temperature, but since it does not actually reach a cracking temperature until it approaches the outlet 11, or at least until it reaches the last portion of the coil 8, it is not subjected to a cracking temperature in the coil long enough forwany material decomposition.

As an example to illustrate the time element or factor necessary to cracking, I have discovered that in order to obtain a conversion of paraiiin base gas oil it is necessary to hold it at a temperature of 850 F., under. a pressure exceeding 200 pounds for about15 minutes. In the ordinary operation of my process the oil will be at a cracking temperature in the discharge end of coil 8 for a fraction of a minute only. As a result there is practically no carbon formed in the coil and consequently the coil will last almost indefinitely.

After the oil has absorbed the heat necessary for decomposition it is passed directly through the connecting pipe 11 to the converters D in which large bodies of oil are maintained, the liquid level being substantially as indicated in the drawings. Here the oil, while still under the same pressure to which it was subjected in the heating coil, is maintained at a cracking temperature for the time necessaryfor decomposition. Of course, there may be some reduction in pressure in the converters, possibly as much as pounds,

' due to the fact that the friction of the pipe 8 will augment somewhat the pressure in the verters ispreferably held at that at which there is an efiicient rate of decomposition. By way of example, it may be stated that in converting paraflin base gas oil I have held the converters at a temperature of from 750-- 850 F. under a pressure around 200 pounds. When cracking a lower boiling hydrocarbon, such as the kerosene fractions, I have used substantially the same temperatures with a pressure around 300 pounds. In each case the temperature in the heating coil outlet was maintained at about 50 higher than that of the converters.

The highly heated oil is introduced into the bottom of still 12 and overflows through the line 15 into'the still 13. The residual oil is drawn off through either or both of the lines 28 and 29 and there is consequently produced a positive flow of oil up through the converter 12 and down through converter 13. The outlets 24 and 25 are not ordinarily used except for an emergency or at the end of a run.

The stills are not required. to stand the high furnace temperatures commonly sought to be applied to cracking stills because the oil enters the stills at such a high temperature and only a moderate heat is necessary to mainta n the cracking temperature. -'Consequently, carbon is deposited on the still walls in less quantities and in a softer condition so that it may be removed readily by the scrapers 18 and the life of the stills is thus greatly prolonged. The heat contained in the oil entering the still 12 maintains the body of oil in through the vapor line 41 to the separator E.

It is best that the vapor line be made of as short length as practicable and that it have little or no upward incline as I desire to avoid as far as possible the cooling effect upon the still 13 of the return thereto of any condensate through the vapor line. For safety purposes the pipe 41 may well have a slight incline, but in order to get the best results with my apparatus it is not desirableto permit any extensive backtrapping into the converters, as to do so will make necessary a higher temperature in the furnace 16.

. The temperature in the separator E is so regulated that those hydrocarbons of less volatility than desired for the final product are condensed, while the volatile product desired is allowed to pass out through the line 58 in the form of vapor. -To facilitate the description of the-process I use the term kerosene as an example of the product condensable in the separator and the term gasoline as an example of the volatile product which leaves the separator in the form of vapor. Bearing in mind then that these terms are used by way of example, and'not in a limiting sense, the kerosene is condensed in the primary separator, drops down from drum 45 through the pipes 46 and comes in contact with the heated vapors entering the drum 44 so that any gasoline entrapped in the condensate is revaporized while the kerosene falls into the backtrap pipe 55-.

The gasoline vapors passing through the line 47 to the light separator 43 will COD.

sive portions of entrapped liquid and thus insure that a maximum portion of the volatile product desired is ultimately passed out through the vapor line 58 in the form of a homogeneous vapor, while at the same time the back flowing condensate is employed to cool the vapors.

The condensate such as kerosene is returned to the heating coil 8 through the line kerosene fractions which are produced so abundantly in the cracking operation are continuously returned to the heating coil 8, a constant ratio of charge to backtrap being maintained and in this way the kerosene fractions are ultimately reduced to gasoline. The constant circulation through the system of the easily vaporizable kerosene constituents creates a heat cycle which assists in maintaining the required degree of heat in the heating coil and converters and lessens the amount of external heat required to be applied thereto.

The vapors uncondensed in the separators E pass through the vapor line 58 to the condenser F where the gasoline, naphtha or other hydrocarbon product desired is condensed. The distillate is collected in the receiver 64 and is withdrawn, as desired, through the outlet 67. The permanent gases escape through the pipe 65. By controlling the escape of the permanent gases by means of the valve 66 an effective control of the pressure in the system may be obtained.

The following may be given as a specific example of the invention: An apparatus of the type described herein comprising a battery of two or more converters is used for the conversion of paraflin base gas oil. The oil after being preheated in the exchanger A and economizer B is charged into the heating coil C at the rate of about 5070 barrels per hour. The temperatureat the heating coil outlet is maintained constantly at about 850 F. which permits a. constant temperature in the converters of about 775 F. or higher. The oil is passed from the heating coil directly into the first still 12 (or with the four-still battery shown in Figure 8 the oil may be passed through the branch lines 11a and 11b to the first two stills 12a and 12?), respectively), and flows to the other still 13 (or to the remaining stills 13a and 13b in succession). A constant oil level is maintained in the converters, as denoted by gages 40. Distillate is drawn off from the receiver 64 at the rate of about 25 barrels per hour and residue is drawn oil from the last still 13 at the rate of about 35 barrels per hour. The charge into the converters is at the rate of approximately 25% of their liquid capacity per hour. The distillate is withdrawn at the rate of about 10% of the liquid capacity of the converters per hour and the residue at the rate of about 15% of the liquid capacity of the converters per hour. The kerosene fractions are taken care of as formed, being separated out in the separators E and forced back into the heating coil thus maintaining a constant ratio of backtrap to charge entering the heating coil C and forming a constant cycle of the kerosene fractions through the system. A pressure around 200 pounds is maintained throughout the apparatus. It is understood that I do'not intend to limit the scope of my invention by the mention of the specific temperatures, rates of flow, etc., which are given in this instance of the use of my invention, and that this specific case is given merely as an example of the invention.

the fact that little or no crackin occurs therein. Another explanation of t e remarkable length of life of the coils 8 employed in my system may reside in the fact that even if there is some decomposition therein it is a decomposition without carbon formation.

My experiments tend to show that in the first stages of cracking there is. little or no formation of hydrocarbons of the gasoline group and practically no formation of carbon, but rather a breaking down into more intermediate products, such as those of the kerosene group. At any rate, there is no substantial formation of either gasoline or carbon until the oil has been held at a cracking temperature and pressure for a considerable length of time in the converters, as required.

In the ordinary operation of my process I prefer to convert oils from which the gasoline content has already been removed by fractional distillation and thus reserve the apparatus solely for the conversion process in which higher boiling hydrocarbons are actually decomposed into lower boiling ones. At times it is convenient, however, to convert an oil which may already contain certain proportions of the more volatile oils. For example, a crude oil having a gasoline content in its natural state may be utilized. When operating upon a crude oil or other oil which contains a greater or less amount of gasoline or other volatile oils it is convenient to use the apparatus shown in Figure 7 which serves the function of a separator of the volatile products from the condensate and also as a preheater of the oil to be treated and as a means for distilling off the more volatile fractions. The vapor line 41 conducts the vapors from the converters to the primary separator 42. The vapors uncondensed in the primary separator pass through the pipe 47 to the secondary separator 43. Each separator is provided with a number of baflle plates or distilling pans 79 to collect the back flowing condensate and to enable the lighter constituents thereof to be vaporized by means of the heat of the vapors, the condensate line 51 bringing the liquid from the light separator into contact with the vapors in the heavy separator. The crude oil or other oil to be treated is charged through the line 7 (with or without having been preheated in exchanger A or economizer B) into the upper part of the separator 42. The oil charge, as well as the returning condensate, flowing I attribute the longevity of the tubes 8 to down over the distilling pans is vaporized by the heat of the vapors and thus the charge is stripped of its lower boiling point constituents, after which it is passed together with the condensate into the line 55 and charged into the heater coil 8. In this way'by a single continuous operation the oil is fractionally distilled to recover its more volatile contents and the residue is then converted into more volatile products through molecular decomposition of the hydrocarbons.

Obviously, many modifications in the apparatus and mode of operation may be made without departing from the spirit of the invention which is defined in its true scope in the appended claims.

What I claim is:

1. A process of cracking oil, consisting in passing the oil through a heating coil wherein it is subjected to cracking conditions of heat and pressure, in transferring a portion of the oil from said coil into a primary expansion chamber, in directing all of the oil constituents from said primary expansion chamber to a secondary chamber, and in introducing the remaining portion of the heated oil from saidcoil directly into the liquid oil in said secondary expansion chamber to increase the conversion therein.

2. A process of cracking oil, consisting in passing the oil through a heating coil wherein it is subjected to cracking conditions of heat and pressure, in transferring a portion of the oil from said coil into a primary expansion chamber, in directing all of the oil constituents from said primary expansion chamber to a secondary chamber, and in introducing the remaining portion of the heated oil from said coil directly into the liquid oil in said second expansion chamber to increase the conversion therein, in taking off vapors from said second expansion chamber, in dephlegmating such vapors, in condensing the dephlegmated vapors and collecting the resulting distillate, and in returning the reflux condensate resulting from the dephlegmation of the vapors to the heating coil for further treatment.

In witness whereof I have hereunto set my hand this 8 day of November 1927.

OTTO BEHIMER. 

